Effects of basic density, annual growth and drying schedule on selected quality factors of dried Siberian larch (Larix sibirica) timber

Abstract

Siberian larch (Larix sibirica Ledeb.) timber is suitable for many uses in the mechanical wood industry. Drying it without any decrease in value, however, is difficult and slow. The purpose of this research was to compare the drying quality of Siberian larch timber dried with three different conventional schedules taking into account the density and annual growth of wood. Five drying tests were performed. The final moisture content (MC), MC gradient, cracks, deformations (bow, crook, twist and cup) and case hardening were measured from the dried timber. The basic density particularly affected the MC, as shown in the differences regarding dried wood, with the denser wood having higher final MC and MC gradient. It was also found that large annual growth increased some deformations. Most of the measured factors were best after drying at the highest temperatures used; however, a slightly different trend was observed for bow, twist and cup. MC factors and twisting were the most problematic properties in drying according to this study. Sorting Siberian larch timber, particularly according to density, would improve the MC properties of dried timber by ensuring sufficient drying time, as economically as possible, for each timber piece.

Keywords:

• Bow
• case hardening
• conventional drying
• cracking
• crook
• cup
• deformations
• moisture content
• twist

Acknowledgements

We thank Mr Kari Kuhmonen and Mr Timo Aavakallio of the YTI Research Centre for consultations in project administration and drying research. We are grateful to Mr Teijo Nikkanen and other involved people from Punkaharju Research Station, Finnish Forest Research Institute, and Mr Jukka Huomolin from Pariwood Oy, Parikkala, Finland, for organizing the Finnish and Siberian timber, respectively. This research belongs to the SIBLARCH project: “Decay resistant timber—Siberian larch compared to Scots pine in forestry and products”. The project was carried out by several public organizations and private companies in Finland, Iceland, Norway, Russia and Sweden. The project has been partly financed by the European Union (European Regional Development Fund) within the INTERREG IIIB Northern Periphery Programme.

Additional information

Notes on contributors

Samuli Heikkonen

Current address: Metsäliitto Cooperative, Finnforest, Plywood, PO Box 42 (Vaneritehtaankatu 1), FI-44201 Suolahti, Finland